Dog Castration: a step by step guide to the operation

by Jenny Sheriff BVM&S MRCVS

Deciding whether to castrate or not

Castrating or neutering a male dog is an operation requiring a general anaesthetic. Both testicles are removed. As with all operations, the advantages and disadvantages should be considered carefully before deciding. Your own vet is the best person to advise you about your particular dog, but the following general advice may also help.

The main advantages of castrating a male dog are prevention of breeding, prevention of testicular cancer, reduction in the risk of prostate problems (including prostate cancer) and modification of certain behaviours. Only behaviours which are related to male hormone levels will be improved, so castration is never an alternative to proper socialisation and training. For example, a tendency to escape and run away will improve if your dog is chasing the scent of a bitch in season, but not if your dog is just untrained and wilful. An aggressive dog can be improved by castration if the cause is related to his male hormone levels, but not if your dog has not been well socialised and is afraid of people and other dogs.

The main disadvantages of having your dog castrated are the risks associated with any general anaesthetic and any operation, but these are very small risks when compared to the potential benefits.

Dog owners often ask whether their dog’s character will be changed by castration. In my opinion it is unchanged unless it is a change for the better (as in certain behaviours mentioned above). Another common worry is that a dog will become overweight and lethargic after castration, but this is 100% preventable with the correct diet and exercise.

Deciding when to castrate

The best age to castrate depends on the reason for doing so. If it is a planned procedure, it might well be carried out at 9-12 months of age, if your vet is happy that your dog is physically mature enough. If castration is advised for behavioural reasons, it might not be obvious until 1-2 years of age that there is a need for it. When castration is carried out later in life, the positive changes might not be quite so great, but your dog is never too old to castrate if there is a medical reason for it, like a testicular tumour.

Dogs with one or both testicles not descended

During development, the testicles move down from inside the abdomen into the scrotum. Usually both will have descended into the scrotum by the time a puppy is seen for vaccinations at around 2 months of age. If one or both testicles have not descended into the scrotum, this will need to be checked later. If either or both of the testicles stays inside the abdomen, they will be at greater risk of developing cancer in later life, so castration is usually advised. The operation to remove an undescended testicle is a more complicated operation than removal from the scrotum. (see The Operation). A dog which has one undescended testicle is called monorchid. If he has two undescended testicles, he is called a cryptorchid.

Before the operation

Your vet will want to check that your dog is in good general health, is the correct weight and has two fully descended testicles in the scrotum.

Another important way of minimising risks is by taking a blood test before the anaesthetic. This could be done on the day of the operation or a few days earlier. This is used to check the liver and kidney function (both vital when dealing with anaesthetic drugs) and to rule out any unsuspected illnesses.

Before going to the surgery

Before any anaesthetic the dog should be starved for a number of hours, according to the instructions of the surgery. Having an empty stomach prevents any problems with vomiting which could be dangerous. It is also a good idea to allow your dog enough exercise to empty the bladder and bowels. Apart from that, it is best to stick as closely as possible to the normal routines of the day so that the dog does not feel anxious.

Being admitted for surgery

On arrival at the surgery, you can expect to be seen by a vet or a veterinary nurse who will check that you understand the nature of the operation and will answer any questions you may have. They will ask you to read and to sign a consent form for the procedure and ask you to supply contact phone numbers. This is very important in case anything needs to be discussed with the owner before or during the operation.

Before the anaesthetic

Your dog will be weighed to help calculate the dosages of drugs and given a physical examination including checking his heart. If a pre-anaesthetic blood test has not already been done, it can be done now and the results checked before proceeding. If any abnormalities are found, these will be discussed with the owner before deciding whether the operation goes ahead or not. One possible outcome is that extra precautions such as intravenous fluids may be given.

A pre-med, which is usually a combination of several drugs, will be given by injection. This begins to make the dog feel a bit sleepy and ensures that pain relief will be as effective as possible.

The anaesthetic

There are several ways in which this can be given, but the most common is by an injection into the vein of the front leg. The effects of the most commonly used drugs are very fast, but don’t last for very long, so a tube is placed into the windpipe to allow anaesthetic gas and oxygen to be given. The anaesthetic gas allows the right level of anaesthesia to be maintained safely for as long as necessary.

Various pieces of equipment will then be connected up to monitor the anaesthetic. This is a skilled job which would usually be carried out by a qualified veterinary nurse. Apart from the operating table, the instruments and the anaesthetic machine, a lot of specialised equipment will be on “stand by” in case it is needed.

The area where the surgical incision is to be made will be prepared by clipping and thorough cleaning to make it as close to sterile as possible. The usual site of the incision for castration is not through the scrotum but just in front of it.

The operation

While the dog is being prepared for surgery as mentioned above, the surgeon will be “scrubbing up” and putting on sterile clothing (gown, gloves, hat & mask). The surgical instruments will have been sterilised in advance and are opened and laid out at the start of the operation.

The operation involves removal of both testicles. They are removed by cutting carefully through the skin just in front of the scrotum, and through the various layers which cover the testicle. The very large blood vessels and the spermatic cord have to be tied carefully before cutting, allowing removal of the testicle. The layers are then closed up with sutures, which may be visible on the surface or may be buried. Further drugs can now be given as needed.

The usual site of the incision for castration is shown by the arrow. The skin will be shaved and thoroughly cleaned before the operation.

The usual site of the incision for castration is shown by the arrow. The skin will be shaved and thoroughly cleaned before the operation.

If one or both testicles are not in the usual place, the operation to remove them is more fiddly. Occasionally a testicle can be partly descended so that it lies in the groin area, and can be removed in a similar way to a normal testicle but through a separate skin incision. If the testicle is still lying right inside the abdomen, it can only be removed by opening up the abdomen, which is a much bigger operation for your dog and needs a longer recovery time. These testicles are often abnormally small, so can be hard to locate as well.

When the operation is finished, the gas anaesthetic is reduced and the dog begins to wake up. He will be constantly monitored and the tube removed from his windpipe when he reaches the right level of wakefulness.

Recovery

Your dog will be placed in a warm kennel with soft bedding and watched closely during recovery. Most dogs will feel very drowsy at first and will take most of the day to sleep off the effects of the anaesthetic. Your dog will only be allowed to come home when he is awake enough to stand and walk unaided.

After-care

Full instructions should be given by the surgery concerning after-care, including when your dog can be offered food and water. The most important things would be to check the appearance of the wound, to prevent your dog from licking it (with a plastic bucket-collar if necessary) and to limit his exercise by keeping him on the lead. Any concerns of any kind should be raised with the surgery.

The scrotum is not removed during surgery, so it can appear at first as if nothing has been removed, especially if there is a little swelling after the operation. However, the scrotum will gradually shrink as time goes by. If you are not sure whether the amount of swelling after the operation is normal or not, always telephone your surgery for advice.

Any medication supplied should be given according to the instructions. Pain relief can be given by tablets or liquid on the food. Antibiotics are not always needed, but may be supplied if there is a need for them.

Usually there will be stitches in the skin which need to be removed after about 10 days, but sometimes these are concealed under the surface and will dissolve by themselves. Your surgery will arrange an appointment for any follow-up checks that are needed.

The effects of castration can take a few weeks to be seen. If your dog is being castrated to prevent breeding, it is important to realise that he may still be fertile for a while after castration.

If all goes to plan, your dog should feel quite normal within about 1-2 weeks of the operation, or a little longer if the testicles were internal.

Click here for information on the bitch spay operation – female dog neutering

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